QUANTUM EFFECTS IN AR-SCATTERING - A SEMICLASSICAL INTERPRETATION(HF ROTATIONALLY INELASTIC)

Invoking a semiclassical approach to state-to-state rotationally inela stic scattering, this study seeks to determine the origin of several n ovel features observed in earlier quantum mechanical calculations [Raw luk et al, Chem. Phys. Lett. 202, 291 (1993)]. These features were abs ent from comparable classical trajectory calculations. The semiclassic al (classical path) method used here treats the relative motion of Ar and HF classically, while the HF rotation is treated quantum mechanica lly by expansion in a rigid rotor basis set. This semiclassical approa ch reproduces the exact quantum results very well. The time dependence of the classical path allows a detailed study of the role played by t he potential energy surface governing the dynamics. In particular, the behavior of the expansion coefficients [Y(jm)\PSI (t)] in the complex plane is very revealing. From this analysis, it is clear that the qua ntum effects stem from a balance between the attractive and repulsive parts of the potential.